The Control Of Respiration Is A Non Conscious Act

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The control of respiration is a non-conscious act that is maintained in the brain through neuronal control. Overall, what initiates and controls respiration and ventilation resides in the respiratory control centers of the brain: the medullary respiratory center, pons respiratory center, and pre-Botzinger complex. The pre-Botzinger complex is an area in the upper end of the medulla that is responsible for the baseline rhythmic activity in respiration (Ramirez). During quiet breathing, the dorsal respiratory group (DRG) relays action potentials to the phrenic nerve and intercostal nerves, generating contractions of the diaphragm and intercostal muscles that result in inspiration; expiration however is passive in quiet breathing through the relaxation of the muscles. For forceful respiration, signals activate the VRG, which leads to the stimulation of motor neurons that generate more inspiratory muscles that initiate active expiration (Sherwood, 2010, page 500). Static lung volumes can change between different ranges depending on the intensity of inspiration and expiration. Pulmonary stretch receptors that lie throughout the smooth muscles surrounding the airways determine the maximum amount of expansion in the lungs. The stretch receptors prevent over inflation of the lungs and the maximum lung capacity through the phenomenon known as Hering-Breuer reflex (Sherwood). In contrast, the maximum amount of deflation in the lungs is dependent on the transmural pressure gradient.

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